The karst region of NW Arkansas is home to many freshwater endemic Species of Greatest Conservation Need (SGCN). Spring headwater endemics include Meeks Short-pointed Crayfish (F. meeki brevis) and Least Darter (E. microperca). NW Arkansas is experiencing rapid urbanization, with increasing prevalence of impervious surfaces and construction of culverts, bridges, and fords. Road crossings can pose barriers to biotic passage and cause stream habitat fragmentation and degradation. To evaluate the effects of road crossings on aquatic SGCN’s and their habitat, 30 headwater streams were sampled throughout NW Arkansas. At each site, fish, crayfish, and macroinvertebrates were sampled, road crossings were evaluated using the Southeastern Aquatic Resource Partnership’s (SARP) Stream Crossing Assessment Protocol and stream habitat variables were assessed using EPA physical habitat protocols. Results indicated stream sites with road crossings had significantly higher water temperatures and conductivity, more embedded substrates, and increased levels of bank incision. Abundance of narrow range endemic crayfishes was positively correlated with both higher dissolved oxygen levels and higher SARP scores (less severe barriers). Building on our understanding of how road crossings influence stream habitats and species distributions, we also sought to examine habitat associations of the Least Darter across its broader range. By comparing our Arkansas data with habitat data from northern populations obtained by the Minnesota Pollution Control Agency, we found Least Darter habitat in northern Minnesota streams tended to be deeper, more conductive, and potentially warmer than AR streams. Understanding correlations between rare and endemic species both in relation to local factors as well as across their range is important to understanding critical habitat needs.